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For centuries, the ill effects of noise exposure in the workplace have been recognized as a principal cause of hearing loss. Evidence of hearing impairment in workers involved in, for example, blacksmithing and mining, has been documented in the Middle Ages (Berger, 2000) and cited in the medical literature of the nineteenth century (Fosboke, 1831). The problem of occupational hearing loss has been recognized as one of the most common work-related diseases in the United States. In 1998, the National Institute for Occupational Safety and Health (NIOSH) estimated approximately 5 million workers had daily time-weighted average (TWA) exposures in excess of 85 dBA (NIOSH, 1998). More recent estimates place this figure at 24 million workers based upon the National Health and Nutrition Examination Survey data (Tak et al., 2009). Using the National Occupational Exposure Health Survey data (NIOSH, 1988) as well as reports issued by the Booz-Allen Hamilton (1983) and the Bolt et al. (1976), Franks (1988) estimated that 95% of daily TWA exposures were less than 95 dBA. Although the TWA exposures represent an average over a day and are not necessarily indicative of instantaneous noise levels, such a statistic suggests that noise exposures can be reduced to a safe level.